Calculate the volume of the gas at STP: 45 g of hydrogen gas.

To calculate the volume of the gas at STP, we can use the ideal gas law equation:

PV = nRT

Where:
P = pressure (1 atm)
V = volume
n = number of moles
R = ideal gas constant (0.0821 L.atm/mol.K)
T = temperature (273 K at STP)

First, we need to calculate the number of moles of hydrogen gas using its molar mass:

Molar mass of hydrogen (H2) = 2 g/mol

Number of moles = mass / molar mass
Number of moles = 45 g / 2 g/mol
Number of moles = 22.5 mol

Now, we can substitute the values into the ideal gas law equation:

(1 atm) * V = (22.5 mol) * (0.0821 L.atm/mol.K) * (273 K)

V = (22.5 mol * 0.0821 L.atm/mol.K * 273 K) / 1 atm
V = 500.3625 L

Therefore, the volume of 45 g of hydrogen gas at STP is 500.3625 liters.

Step 1: Convert mass of hydrogen to moles

- Molar mass of hydrogen (H2): 2.016 g/mol
- Moles of hydrogen (n): 45 g / 2.016 g/mol = 22.33 mol

Step 2: Calculate volume of gas at STP

- Standard temperature (STP): 273.15 K (0 °C) and 1 atm (101.325 kPa)
- Ideal gas law: PV = nRT
- Volume (V) = nRT/P
- Substitute values: V = (22.33 mol - 0.0821 L atm/(mol K) - 273.15 K) / 1 atm = 492.6 L

Therefore, the volume of 45 g of hydrogen gas at STP is 492.6 L.